Manifestly, it is extremely desirable for reasons of efficiency that the machine carry the maximum inventory possible within its space limitations. To this end, the product carriers secured to the conveyor of the machine follow a rectangular or elliptical path of travel with vertical parallel stretches and rounded corners which conform as closely as possible to the dimensions of the product cabinet. In this manner the carriers may be disposed in close proximity to one another on the conveyor without interfering with each other during changes of directions at the limits of the conveyor. A number of control problems have existed in the past, and continue to exist since the carriers must be allowed to remain horizontal relative to the conveyor. Since the machine may be required to handle items which would be disturbed when upset, the item supporting surfaces of the carrier must be maintained in planes that do not depart substantially from the horizontal as the carriers move through the upper and lower limits of their travel.
One attempt to solve such control problems is shown in U.S. Pat. Nos. 3,556,284 and 3,770,105 wherein support arms are secured to a carrier, the arms requiring followers which are pivotally connected to the carriers and move longitudinally within slots formed within each arms while maintaining an engagement with an elliptical-type track. Engagement of each carrier with either bias mechanism mounted at the top and base of the cabinet, or with the top and base themselves, however, is necessary to ensure non-tilting of the carriers as they move through the upper and lower reaches of the path.
Another attempt involved carriers mounted at opposite ends in a pivotal manner at opposed locations below the center of gravity of the carriers whereupon the carriers continually tended to roll over and bind against each other particularly at the rounded corners of the elliptical path, due partly to gravity working against the stability of the carriers.
It is to the elimination of such problems that this invention is directed, including the provision of improved product carrier sensing for displaying cost and to improved cabinet support in servicing position.